I'm sorry if my question is so begginer...
I appriciate if someone help me to findout how to make the backgrond (which its default is White) as "No colour"?
You cannot make it transparent in Flash--it has to have a color, white by default. If the file will be displayed in a web page then you control whether or not the background shows by setting the wmode property in the html embedding code. You can set this up in the html section of the Publish Settings, or you can just set it in the web page. When you assign wmode="transparent" the background will not appear.